Return to Contents Chapter 14: Organometallic Compounds Ch 14 contents
Organometallic Answers
 
Qu 1: Remember, organometallic compounds contain carbon-metal bonds
  (a) CH3CH2ONa :  No, since it is an oxygen-metal bond
(b) CH3CH2Li : Yes there is a carbon-metal bond
(c) CH3CH2BH2 : No, boron is a non-metal
(d) (CH3CH2)2Zn : Yes there are 2 carbon-metal bonds
(e) CH3CH2MgBr : Yes there is a carbon-metal bond
(f)  CH3C≡CNa : Yes there is a carbon-metal bond
   
Qu 2: (c)  Metals are electropositive and carbon is electronegative with respect to a metal.
   
Qu 3:           CH3CH2- >  CH2=CH- >  CH3C≡C- >  CH3CH2O-  >  CH3CH2OH         (check pKa's)
  A good way to think of basicity is the ability of the basic atom to donate it's pair of electrons (Lewis definition).
Factors such as electronegativity and hybridisation are important. Electronegative atoms are poor electron donors since they hold onto their electrons.  sp orbitals are more electronegative then sp2 due to the higher "s" character. Likewise for sp2 over sp3. 
   
Qu 4: The Grignard reagent  CH3CH2MgBr gives the following products:
 
(a)  3-pentanol,  CH3CH2CHOHCH2CH3 (b)  1-phenyl-1-propanol,  C6H5CHOHCH2CH3
(c)  2-methyl-2-butanol, (CH3)2COHCH2CH3 (d)  deuteroethane,  CH3CH2D  (due to acidic D)
(e)  3-phenyl-3-pentanol, C6H5COH(CH2CH3)2 (f)   ethane,  CH3CH3(due to acidic H)
(g)  ethane,  CH3CH3(due to acidic H) (h)  no useful reaction
   
Qu 5: Cuprates are prepared by adding Cu (I) halides to organolithium reagents, so we must first prepare the organolithium reagent.
 
   
Qu 6: The cuprate (c) is the best choice.  Organolithiums and Grignard reagents are too basic for coupling reactions for alkane synthesis.  Organozinc reagents are not reactive enough.
   
Qu 7:  
 
organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary